What is a concrete moisture test?

A concrete moisture test is used to determine how much moisture is present – usually in order to know if flooring can be safely installed without causing issues. Measuring the moisture of a concrete slab can be done in several ways, but currently the only methods approved by Australian standards measure the relative humidity of the slab. The most common method, uses in-situ probes (ASTM F2170). In this method holes (at least 1 / 100m²) are drilled to a specific depth in the slab, a sleeve is installed into the holes to create a small chamber with an open base inside the slab.  This allows the air inside the chamber to equalise to the relative humidity of the slab. The sleeve is left for a minimum of 1 day for the chamber to equalise with the concrete slab. Following the equalising period, the relative humidity is read using a thermohygrometer or relative humidity sensor.